.\"     $OpenBSD: harmony.4,v 1.9 2007/05/31 19:19:54 jmc Exp $
.\"
.\"
.\" Copyright (c) 2003 Jason L. Wright (jason@thought.net)
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd $Mdocdate: May 31 2007 $
.Dt HARMONY 4 hppa
.Os
.Sh NAME
.Nm harmony
.Nd CS4215/AD1849 audio device
.Sh SYNOPSIS
.Cd "harmony* at gsc? irq 13"
.Cd "audio*  at harmony?"
.Sh DESCRIPTION
The
.Nm
device uses the
.Tn Crystal Semiconductor
.Tn CS4215
16-Bit Multimedia Audio Codec
or
.Tn Analog Devices
.Tn AD1849
.Tn SoundPort(R) Stereo Codec
chip to implement the audio device interface described in
.Xr audio 4 .
This device is found on most
.Tn HP PA-RISC
workstations.
The
.Nm
has a maximum precision of 16 bits and has a stereo input and stereo output.
.Pp
On
.Tn HP 9000/712
models
.Nm
also provides two additional channels for an add-on
card with two fax/voice modems.
.Pp
One of the hardware registers reflects the state of the
.Tn CHI
bus that is used to communicate with the codec and thus
being sampled at a low accuracy secondary frequency
(such as
.Xr timeout 9 )
produces poor quality random bit stream that is fed into the
entropy pool of
.Xr random 4 .
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr audio 4 ,
.Xr gsc 4 ,
.Xr intro 4 ,
.Xr random 4
.Sh HISTORY
.Ox
support for
.Nm
first appeared in
.Ox 3.3 .
.Sh CAVEATS
To trigger entropy collection
.Tn CHI
bus has to be programmed into the data mode that happens once
a single buffer of data has been played or recorded.
